Directional drilling method.

摘要

The direction of drilling of a well bore is changed by forming a cement plug in the well bore at a location therein where the direction of drilling is to be changed and drilling a pilot hole in the plug. The cement plug is formed using a particular slurry comprising a mixture of water and hydraulic cement in a weight ratio of from 0.5:1 to 5.0:1; the particle size of said hydraulic cement is no greater than 30 microns; and the Blaine Fineness of said hydraulic cement is no less than 6,000 cm<2>/g. The use of such finely divided hydraulic cement significantly reduces the waiting time required for the slurry to develop compressive strength.